Internal combustion engines that can be operated at least partly on gaseous fuel include gaseous fuel internal combustion engines and dual fuel (DF) internal combustion engines. DF internal combustion engines can typically operate in a liquid fuel mode (LFM) and in a gaseous fuel mode (GFM). An exemplary DF internal combustion engine is disclosed, for example, in European Patent Application No. 13 174 377.5 by Caterpillar Motoren GmbH & Co. KG, GERMANY, filed on 28 Jun. 2013. In LFM, a liquid fuel, such as Diesel fuel or heavy fuel oil (HFO), is provided as the sole source of energy during combustion via a main liquid fuel injector. In GFM, a gaseous fuel such as natural gas is provided, for example mixed with air in an intake port of a cylinder. Ignition of the gaseous fuel may be performed with a small amount of liquid fuel that is, for example, injected directly into the cylinder via the same main fuel liquid injector or a separate ignition fuel injector.
In gaseous fuel internal combustion engines and DF internal combustion engines, for each cylinder at least one gaseous fuel admission valve, herein also referred to as gas admission valve (GAV) may be positioned between a source of gaseous fuel and an air intake of the engine. When a GAV is opened in GFM of the DF engine, or during operation of the gaseous fuel engine, the gaseous fuel passes into the air intake for mixing with the intake air.
An example of a solenoid actuated gaseous fuel admission valve is disclosed in European Patent 1 040 264 B1. Solenoid actuated GAVs include a solenoid coil, a movable plate, and a stationary plate or disc, whereby a current delivered to the solenoid coil actuates the valve by lifting the movable plate from the stationary plate.
Due to their positioning close to the combustion chamber, GAVs may be susceptible to contamination and increased wear. For example, during operation in LFM, the movable plate of a solenoid actuated GAV may dither on the stationary plate or disc of the closed gaseous fuel admission valve due to the combustion. Thereby, both movable plate and stationary plate or disc may be exposed to an increased wear. Furthermore, GAV may not only open in GFM but may also open during LFM. For example in case of a solenoid actuated GAV, a pressure difference between intake air and the gaseous fuel pipe system during LFM may result in opening. Then, small particulates may get trapped in the valve, for example, between the movable plate and the stationary plate or the seat of the solenoid actuated GAV and the valve may no longer close properly. Wear as well as contamination of the GAV may result in leakage, increased pass rate, or even a stuck open GAV.
The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems.